In a typical radio data communication system having one or more host computers and multiple RF terminals, communication between a host computer and an RF terminal is provided by one or more base stations. Depending upon the application and the operating conditions, a large number of these base stations may be required to adequately serve the system. For example, a radio data communication system installed in a large factory may require dozens of base stations in order to cover the entire factory floor.
In earlier RF data communication systems, the base stations were typically connected directly to a host computer through multi-dropped connections to an Ethernet communication line. To communicate between an RF terminal and a host computer, in such a system, the RF terminal sends data to a base station and the base station passes the data directly to the host computer. Communicating with a host computer through a base station in this manner is commonly known as hopping. These earlier RF data communication systems used a single-hop method of communication.
In order to cover a larger area with an RF data communication system and to take advantage of the deregulation of the spread-spectrum radio frequencies, later-developed RF data communication systems are organized into layers of base stations. As in earlier RF data communications systems, a typical system includes multiple base stations which communicate directly with the RF terminals and the host computer. In addition, the system also includes intermediate stations that communicate with the RF terminals, the multiple base stations, and other intermediate stations. In such a system, communication from an RF terminal to a host computer may be achieved, for example, by having the RF terminal send data to an intermediate station, the intermediate station send the data to a base station, and the base station send the data directly to the host computer. Communicating with a host computer through more than one station is commonly known as a multiple-hop communication system.
Difficulties often arise in maintaining the integrity of such multiple-hop RF data communication systems. The system must be able to handle both wireless and hard-wired station connections, efficient dynamic routing of data information, RF terminal mobility, and interference from many different sources.
The present invention also relates to a wireless and wired communication network used to maintain communication pathways among wireless communication devices and remote stations. As is well known, wired local area networks ("LANs"), such as ethernet utilizing coaxial or twisted pair cabling ("wiring"), provide communication among remote stations, such as personal or host computers, which are commonly wired to a wired LAN. Hereinafter, a wired LAN is referred to as a "wired subnet". To maintain communication beyond the wired range of ethernet, for example, bridging devices are employed to route information between one wired section of ethernet to another wired section. The bridging devices forward communication from one side of the bridging device onto the other, and vice versa. Smarter bridging devices are also known which keep track of the location of the remote stations so that forwarding only occurs when necessary.
As is also well known, in typical wireless communication networks, wireless communication generally occurs directly between two or more wireless terminals. To overcome transmission range limitations, such wireless networks have included wireless relaying transceivers to relay received communication, extending the range at which communication can be maintained. However, depending on the mode of wireless communication, many wireless relaying transceivers may be needed to adequately serve the network requirements.
In earlier wireless communication systems, the wireless relaying transceivers were also used to manage communication among a variety of wireless communication devices. Such relaying transceivers have been called base stations. The base station were typically connected directly to a host computer through multi-dropped connections to an ethernet communication line. To communicate between a wireless communication device and a host computer, in such a system, the wireless communication device sends data to a base station, and the base station passes the data along a hard-wired ("wired") link to the host computer.
In order to cover a larger area with a wireless communication system and to take advantage of the de-regulation of the spread-spectrum radio frequencies, later-developed wireless communication systems are organized into layers of base stations. As in earlier wireless communications systems, a typical system includes multiple base stations which communicate directly with wireless terminals and the host computer.
In such wireless networks, difficulties often arise in maintaining the integrity of wireless communications. The wireless communication network must be able to handle both wireless and wired connectivity, efficient routing of data information, wireless communication device mobility, and interference from many different sources.
Customarily, wired local area networks support wireless communication devices that occupy fixed locations. Message traffic to and from such devices are routed via paths that do not change with time. Absence of a communication link to a device reflects a fault condition, i.e., a breakdown in some network component.
Thus, one object of the present invention is to route data through a wired and wireless communication network efficiently, dynamically, and without looping.
Another object of the present invention is to make the routing of data transparent to wireless terminals and remote stations located on IEEE 802.3 type subnets.
It is a further object of the present invention for the network to be capable of handling wireless communication device mobility and lost network nodes with minimal impact on the entire data communication system.
It is a still further object of the invention to allow wireless mobile computing devices, a type of wireless communication device, to move freely within wireless networks consisting of many relay nodes while transparently maintaining network connectivity with a plurality of wired subnets.